Sema: Forbid variadic templates in explicit DSAs

Fixes llvm#21

Author: mikaoP

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -9749,6 +9749,8 @@ def err_oss_typecheck_shaping_base_no_ptr_or_array: Error<
   "shaping expression base is not a pointer or array">;
 def err_oss_shape_incomplete_type : Error<
   "shape of pointer to incomplete type %0">;
+def err_oss_variadic_templates_not_clause_allowed : Error<
+  "variadic templates are not allowed in OmpSs-2 clauses">;
 def warn_oss_section_is_char : Warning<"array section %select{lower bound|length}0 is of type 'char'">,
   InGroup<CharSubscript>, DefaultIgnore;
 } // end of OmpSs component.

clang/lib/Sema/SemaOmpSs.cpp

@@ -283,6 +283,7 @@ class DSAAttrChecker final : public StmtVisitor<DSAAttrChecker, void> {
   }
 
 public:
+
   void VisitCXXThisExpr(CXXThisExpr *ThisE) {
     // Add DSA to 'this' if is the first time we see it
     if (!Stack->getThisExpr()) {
@@ -722,9 +723,12 @@ StmtResult Sema::ActOnOmpSsTaskDirective(ArrayRef<OSSClause *> Clauses,
 static std::pair<ValueDecl *, bool>
 getPrivateItem(Sema &S, Expr *&RefExpr, SourceLocation &ELoc,
                SourceRange &ERange) {
-  if (RefExpr->isTypeDependent() || RefExpr->isValueDependent() ||
-      RefExpr->containsUnexpandedParameterPack())
+  if (RefExpr->containsUnexpandedParameterPack()) {
+    S.Diag(RefExpr->getExprLoc(), diag::err_oss_variadic_templates_not_clause_allowed);
+    return std::make_pair(nullptr, false);
+  } else if (RefExpr->isTypeDependent() || RefExpr->isValueDependent()) {
     return std::make_pair(nullptr, true);
+  }
 
   RefExpr = RefExpr->IgnoreParens();
   ELoc = RefExpr->getExprLoc();

clang/test/OmpSs/Sema/task_variadic_templates.cpp

@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -verify -x c++ -std=c++11 -fompss-2 -ferror-limit 100 -o - %s
+
+template<typename T>
+T adder(T v) {
+  return v;
+}
+
+template<typename T, typename... Args>
+T adder(T first, Args... args) {
+  T tmp;
+  #pragma oss task firstprivate(args) // expected-error {{variadic templates are not allowed in OmpSs-2 clauses}}
+  {
+    tmp = first + adder(args...);
+  }
+  return tmp;
+}
+
+int main() {
+  int a = adder(1, 2, 3, 4);
+}